HARDNESS PROPERTIES OF PLASTIC OPTICAL FIBERS BY NANOINDENTATION

Mechanical properties are significant for plastic optical fibers in weaving or knitting processes in textile applications. Both core and cladding in plastic optical fiber contribute to the mechanical properties. Nanoindentation is a promising method to investigate the mechanical properties (hardness, stiffness and Young's modulus) in nanoscale displacement and small load range. Nanoindentation creep as the highly time-dependent deformation has a significant effect on nanoindentation properties of polymeric materials. In present work, core and cladding in both latitudinal and longitudinal cross sections of plastic optical fibers with four diameters were investigated in different conditions (loading rates and holding times) under the maximum load of 0.3 mN. The results show that cladding is softer than core and both strong loading rate and holding time sensitivities on nanoindentation creep no matter in latitudinal or longitudinal cross sections. It is also found that the greater the fiber diameter, the higher the hardness and modulus.